BBC Home
Explore the BBC



Last Updated: Monday August 14 2006 09:53 GMT

Puny Pluto may lose planet title

Pluto was discovered in 1930 by US astronomer Clyde Tombaugh

Space experts are meeting to decide whether our smallest planet Pluto deserves to be called a planet.

The tiny member of the solar system - discovered in 1930 - is in a belt of icy debris.

And scientists have recently discovered other space objects nearby which are bigger than Pluto.

Astronomers must decide whether to call them planets or end Pluto's status as a planet. They will make a final decision next week.

Pluto is about 2,360km (1,467 miles) across and is very different to more familiar planets such as our own Earth, Mars, Jupiter, Saturn or even Neptune, Pluto's nearest neighbour.

Pluto facts
Planet Pluto and moon Charon 1
Pluto is named after the Greek god of the underworld, Hades
An 87-year-old retired teacher from Surrey gave Pluto its name
Pluto is the farthest planet from the sun
Pluto has three moons
Pluto takes 249 years to orbit the Sun

One of the space objects discovered, UB313 - nicknamed Xena - was measured by the Hubble space telescope at 3,000km (1,864 miles) across its diameter, making it quite a bit bigger than Pluto.

About 3,000 space experts in the Czech Republic will make the final decision.

In January, the first ever space mission to Pluto set off.

The craft, which cost £396m, will move at a speed of 16km per second to get to Pluto by 2015.

Called New Horizon, it won't actually land on Pluto, but will pass close by to take pictures of the icy planet and beam them back to Earth.

The planets and how they compare to other planetary objects in size